Rumble Jar Kit

Rumble Jar Cold Brew Kit
one review

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What makes it Mighty?

  • Converts traditional mason jar into a simple cold brew coffee system
  • Secondary Cotton filter is endlessly reusable and machine washable
  • Lid and filter made from food grade silicone and 304 stainless steel

Product Details

Rumble Jar is a next-generation cold brew coffee maker, designed to work in tandem with the classic Mason jar. This 4-piece brew kit is all the equipment you need to make professional-quality cold brew coffee right at home. Just add coffee and water and give it a rumble. Prep time takes less than one minute, and by the morning you'll have delicious cold brew coffee ready to drink.

Each kit includes: 

  • 32oz Wide-Mouth Mason Jar (traditional)
  • Stainless Steel Cold Brew Filter 
  • Food-Grade Silicone Cap
  • Cotton Sock (optional 2nd stage filter)

The Filter—Specifically engineered for cold brew coffee, this is not your run-of-the-mill mesh filter. We built our filter from the ground-up using etched stainless steel construction that's lightweight but shockingly sturdy. The 200 micron holes allow water to circulate at a rate that's ideal for making barista-quality cold brew.
The Cap—Rumble Jar's secret sauce. Our patent-pending cap design allows the filter to be fully-nested inside the Mason jar, without interfering with the Mason jar's natural seal. As a result, your coffee stays both leakproof and airtight. 
The Mason Jar—An ideal brewing + drinking + storage vessel with a legendary seal. Our patent-pending design keeps the seal intact, allowing your coffee to stay fresher since the jar remains airtight and more resistant to oxidation (aka the "coffee killer"). A good seal also keeps it from leaking all over your hands and kitchen.

Use: click here for video

Designed and assembled in USA. Mason Jar, packaging and tags made in USA. Filter and cap made in Taiwan. Cotton secondary filter-bag made in China.


What Others are Saying

mighty bird

Overall Score

one review
Great coffee
Review by Kim B on 5/26
Great coffee

This is my new best friend. So easy to prep the night before and have awesome coffee in the morning. Only downside, which one of us gets to use it? Solution? Buy two 😊

MightyNest Trusted
About Rumble Jar
Coffee...we drink a lot of it. That was our "coffee expertise", at least until early 2017 when Karl got fed up with all of the existing cold brew coffee filters out there and started hacking away on some new ideas he came up with to make a better one. Hans remained skeptical. But Karl converted Hans to cold brew through a combination of sorcery and brainwashing (i.e. having him taste it) until Hans capitulated and saw the light...cold brew was better! Both of us are product designers and creators, and while we're pretty good at developing concepts, we're even better at finding folks who have real expertise to make our ideas come to life. We hunted around and linked up with the perfect manufacturing shop that strictly works on coffee devices, and off we went to designing, prototyping and playing with our different ideas. And talking to the cold brew experts...folks that didn't just learn about it yesterday, but have been seriously playing with cold brew for 10+ years, before anyone was really selling it. This group of folks had seen and made it all, so when they said, "Wow this is a really good idea," we knew we were onto something! So in late 2017, we brought Rumble Jar to life on Kickstarter. Rumble Jar's reception was pretty mind-blowing (over $50K raised in 3 weeks)! People were actually getting excited about a fairly simple cold brew coffee filter that didn't even have a single moving part. So if Rumble Jar can make it on Kickstarter, it can make it anywhere! -Hans & Karl

About MightyNest

We make it easy for families to create a healthy home. Each of our 1000+ products has been thoroughly researched to be free of concerning chemicals, and hand-picked for its quality and design. With products for the whole family, ranging from kitchenware to reusable lunch gear to skincare, it is truly better living made easy.